This is a bilingual snapshot page saved by the user at 2025-6-9 23:12 for https://app.immersivetranslate.com/pdf-pro/fe8add82-1bc6-4276-8292-252ac8ce6525/, provided with bilingual support by Immersive Translate. Learn how to save?
BADR UNIVERSITY IN CAIRO
جامعةبـــدربالقــامرة  Badr University, Cairo

PHYSICAL PHARMACY

Lecture 6

Diffusion and Dissolution

Dissolution is the process by which a solid solute enters into a solution when added to a suitable solvent
Dissolution rate: the rate at which the solid dissolves in a solvent.
The above diagram shows the steps of disintegration, dissolution and absorption of solid drug form tablet or capsule.
The dissolution of a solid drug is the slowest step; hence it is the rate limiting step (RLS) in absorption of such drugs.
The dissolution of solids in a liquid is of two stages
1- An interfacial reaction liberation of solute molecules from the solid phase. The solution in contact with the solid will be saturated.
2- Migration of solute molecules through the boundary layers surrounding the crystal to the bulk of the solution via diffusion or convection, which determine the rate of dissolution.